The present invention is directed toward a process for preventing contamination of a reagent system. The process is especially suitable for performing iron determinations where iron contamination would lead to false results. The process comprises the pretreatment of the reagent delivery system with an organosilane solution to form a protective coating whereby contamination of the reagent system is prevented. Excess organosilane solution is then washed from the reagent delivery system prior to being contacted with the reagent system.
A common characteristic of many reagent systems is that they require a low pH, acidic environment. The acidic nature of these reagent systems can attack the surfaces of reagent delivery system to release various contaminants. This is especially true for iron reagent systems where an acidic environment is required to release the iron from the transferrin such that the chromogen can form a colored reaction product with the liberated iron. The acidic characteristic of the various iron reagent systems creates a serious problem when attempting to perform an iron determination with an apparatus that contains iron-containing surfaces, or when employing a reagent delivery system that contains iron-containing surfaces. For example, when a probe is used to apply a reagent which has a stainless steel needle or where an automated apparatus has stainless steel valves or pipettes, the reagent system, because of its acidic nature, causes iron to be leached out which contaminates the specimen and causes erroneously high iron measurements.
Several approaches have been attempted to solve this problem. One such approach is to manually dispense all the reagents into the specimen. However, this is not practical in attempting to assay numerous specimens. In another approach, the apparatus for performing an iron assay is first pretreated with a sucrose buffer. Unfortunately, sucrose pretreatment requires dedicated equipment and treatment with every run. In yet another approach, the apparatus for performing the iron determination can have all the metal parts replaced with plastic parts; however, this is generally not feasible or desirable for the operation of the apparatus. Therefore, it is desirable to develop a process whereby an iron determination or any other assay can be performed on an apparatus containing metal parts or having iron-containing surfaces which does not contaminate the reagent system and therefore introduce error into the determination.